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# [CIM/Infor-Base] What is Main Path?

## Question

What is Main Path?

Main Path is the same function as the CIM rule made to have the same slope as the layout.

What is Main Path
: This is a path defined by two constraint planes. It is characterized by being linked to the horizontal and vertical curve alignment and by varying in path length.

Example of applied structure, Main Girder for PSC Box / Steel Box Br./ Deck Slab / Median Strip /
Side Barrier / Pavement etc.

Tips

To explain using the image below as an example, this path can be created using an offset value between two constraint planes. These planes are specified by the user in the Default Main Path. The Default Main Path is created automatically in Curve Library Mode or Assembly Unit Mode. The main path can be defined with or without an offset.
In this case, you can understand that the alignment created in Base Mode follows the Default Main Path, and the Main Path naturally changes accordingly.

 Figure. 1 Main Path Concept Figure. 2 Alignment Allocation of Main Path

Info

Now, let me introduce the method to define and use Constraint Path using an example. The purpose of the explanation is to understand the definition method of the path and to compare the resulting differences when the Curve Library assigned to each Path is applied to the layout.

1. Alignment Definition and PSC Beam Curve Library

The Curve Library is created to automatically vary according to the length of the assigned path by setting the position properties of all constraint planes to By Ratio.

 Layout (Horizontal Alignment)- Radius: 50m- Total Length: 50m Curve Library (PSC Beam)- All Constraint Plane Alignment: By Ratio- Total Length: 25m Figure. 3 Layout (Horizontal Alignment) Figure. 4 PSC Beam Curve Library

2. Main Path definition and Layout assignment.

 Base > Library > Assembly > Create - Name : Main Path Assembly Unit > Constraint Entity > Space - Space (Connected-1) - Unit Length : 25.0m / OK(Check) Constraint Entity > Path > Main Path - Select Constraint Plane   : Select the starting point and ending point plane- Offset (y) : 5.0m / OK(Check) Assign Library > Curve- Constraint Path : Select Main Constraint Path- Select the created Main Path using the mouse   / OK( Check ) Figure. 5 Create Main Path (Red Line) Figure. 6 Assign Main Path of Curve Library

 Base > Assembly > Assign- Select 1: Main Path in Select assembly unit- Click Define path > Select segment and   select the layout using the mouse- Click the Add button in the Assigned list   / OK( Check ) Figure. 7 Alignment Allocation of Main Path
When Main Path is assigned to an alignment, the Constraint Path is created by finding the station of the alignment according to the Alignment rule of each Constraint Plane and connecting the space in between to correspond with the shape of the alignment.
Figure 7 shows the image with the PSC Beam Curve Library assigned to the Main Path of 25m by maintaining an Offset (5m) curve assigned to a 50m long alignment.

Therefore, Main Path is a Constraint Path used for structures such as girders or deck slabs, and retaining walls that follow an alignment whose shape changes along the alignment.

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